Butadienyl dyes for photography



United States Patent ABSTRACT OF THE DISCLOSURE Indole butadienyl dyes prepared by reacting an indoliurn compound with a cinnamaldehyde compound have valuable light-absorbing characteristics which make them useful in light-sensitive photographic elements and are bleachable.

This application is a division of copending US. application Ser. No. 393,684, filed Sept. 1, 1964, now US. Patent 3,348,487 issued May 21, 1968.

This invention relates to photography and more particularly to butadienyl dyes and photographic elements containing them.

It is known that light-screening substances are often employed in photographic elements, for example (a) in overcoatings to protect the light-sensitive emulsion from ultraviolet light, especially with color materials, (b) in layers between differentially sensitized emulsions, e.g., to protect redand green-sensitized emulsions from the action of blue light, and ('c) in antihalation layers, on either side of a transparent support carrying the lightsensitive emulsion.

In most cases, and especially when the element contains a color-sensitized emulsion, it is desirable to employ light-screening substances which do not react chemically to affect the general sensitivity or the color sensitivity of light-sensitive emulsions with which they come into contact. It is also desirable to employ light-screening substances which do not dilfuse substantially from the layers in which they are incorporated, either during manufacture of the element or during torage. Finally, it is generally necessary to employ light-screening substances which can be decolorized and/or readily removed prior to or during photographic processing; for many purposes it is particularly convenient to employ light-screening substances which are rendered inelfective in one of the photographic processing baths. For example, in an element to be processed by chemical reversal, it may be convenient to employ a light-screening substance which is rendered ineffective (bleached and/or removed) in negative development in order to facilitate exposure of the residual silver halide.

Numerous substances, including many well-known dyes, have been employed for light-screening in the applications indicated above, but it has proved extremely diflicult to find dyes having the combination of qualities desired. Many are not resistant to diffusion and wander from the layer in which they are coated; many adversely affect the sensitivity of light-sensitive emulsions with which they come into contact. Some are not sufiiciently water soluble to enable incorporation into filter layers from aqueous solutions. Some are not 'bleached or destroyed readily by photographic processing and thus present stain problems in the processed photographic element.

The use of styryl dyes for antihalation protection in backing layers has been known for some time. For example, styryl dyes are disclosed for this purpose in U.S. Patent 1,845,404, issued Feb. 16, 1932. However, few

styryl dyes have been found that absorb in the red spectral region, since the high deviations encountered in the dyes from highly basic nuclei reduce markedly the deepening of the color (that is, shift of spectral absorption to longer wavelengths) usually produced *by increasing the chain length. Styryl dyes of the indole series are very unstable under even mildly alkaline conditions. Styryl dyes have been prepared previously as light-screening dyes that are soluble in organic solvents, do not wander and are bleacha'ble in conventional processing baths. Many of the prior art dyes have a tendency to precipitate in aqueous solutions of hydrophilic colloids such as gelatin, polyvinyl alcohol, albumen, casein, etc. and the organic solvent, such as, acetone or alcohol allows the dyes to penetrate the support and render the dyes themselves very difficult to bleach or destroy in conventional processing baths.

It is therefore an object of this invention to provide a novel class of butadienyl dyes which are useful in lightsensitive photographic elements.

Another object is to provide for use in filter layers and antihalation layers in photographic elements, a novel class of butadienyl dyes, which not only have valuable lightabsorbing characteristics but are more water soluble in neutral or in slightly acid solution than prior art butadienyl dyes and thus are more easily incorporated in the filter layer.

Another object is to provide a novel class of butadienyl light-screening dyes which are less subject to diffusion from the filter layer than are the prior art dyes.

Another object is to provide a novel class of dyes which are bleachable by the photographic developer or fixing solutions during the processing of the photograhic element.

Another object is to provide a photographic element having at least one light-sensitive silver halide emulsion layer and at least one light-absorbing filter layer containing a dye selected from the novel class of dyes of our invention.

Still other objects will become apparent from the following description of our invention in the specification and claims.

We have discovered that these and other objects are accomplished by the use of the novel dyes of our invention, which are included in the following formula:

wherein L represents the hydrogen atom, or a halogen atom, e.g., chlorine, bromine, fluorine, etc.; Y and Y each represent a member selected from the class consisting of the hydrogen atom and the nonmetallic atoms which together form a fused ring attached to the indolenine ring in the 4 and 5 positions, the 5' and 6 positions, or the 6 and 7 positions; R and R each represent a member selected from the class consisting of the hydrogen atom, an alkyl group, e.g., methyl, ethyl, propyl, butyl, etc., and together represent the nonmetallic atoms necessary to complete a cycloalkane group, e.g., cyclopentane, cyclohexane, etc.; R represents an alkyl group such as, a carboxyalkyl group (e.g. carboxymethyl, B-carboxyethyl, y-carboxypropyl, fi-carboxybutyl, w-carboxypentyl, w-carboxyhexyl, etc.), a hydroxyalkyl group, (e.g., ,6- hydroxyethyl, fi-hydroxybutyl, w-hydroxyhexyl, etc.), a carboxyalkylcarbamoyloxyalkyl group (e.g., carboxymethylcarbamoyloxyethyl,

13-carboxyethylcarbamoyloxyethyl, 'y-carboxypropylcarbamoyloxyethyl, w-carboxypentylcarba-moyloxyethyl, 8-carboxyethylcarbamoyloxypropyl, etc.), an a1koxycarbonylalkyl-carbamoyloxyalkyl group a, ethoxycarbonylmethylcarbamoyloxyethyl, methoxycarbonylethylcarbamoyloxyethyl, ethoxycarbonylethylcarbamoyloxyethyl, etc.); a sulfoalkyl group (e.g., fl-sulfoethyl, -sulfopropyl, fi-sulfobutyl, w-sulfohexyl, etc.); and methyl, ethyl, propyl, butyl, hexyl, etc.; X represents an acid anion, e.g., chloride, bromide, iodide, perchlorate, thiocyanate, benzenesulfonate, methylsulfate, ethylsulfate, p-toluenesulfonate, etc.; n represents an integer of from 1 to 2 such that n is 1 only when R contains a carboxy group, and a sulfo group; and Z represents an aryl group (e.g., a phenyl, a tolyl, a propylphenyl, etc.) substituted with an amino group, such as, the amino group, a dialkylamino group, (e.g., N,N-dimethylamino, N,N-dipropylamino, N,N-dibutylamino, etc.), an alkylamino group (eg., N-methylamino, N-propylamino, N- butylamino, etc.), a N-alkyl-N-arylamino group (e.g., N-methyl-N-phenylamino, N-butyl-N-phenylamino, N-

ethyl-N-phenylamino, etc.), an alkoxy group (e.g., methoxy, ethoxy, propoxy, butoxy, etc.) and the hydroxy group.

Our dyes are produced to advantage by heating, preferably under reflux, a compound having the formula:

Y; I C-CHa L ii 2 (X )n! with a compound having the formula:

properties make our dyes particularly valuable in redlight-absorbing backing layers for photographic elements. The acid substituted dyes of our invention are particularly useful with basic vehicles, such as, the cellulose esters of dimethylamino acetic acid.

Among the dyes of our invention are the following typical examples which are intended to illustrate but not limit the scope of our invention.

DYE 1 Anhydro 2 (4 p-dimethylaminophenyl-l,1-dimethyl-1, 3-butadienyl) 3 (4-sulfobutyl)-lH-benz[e]indolium hydroxide r zntnsot Anhydro 3-(4-sulfobutyl)-1,1,2-trimethyl-1H-benz[e] indolium hydroxide (1 mol., 6.9 g.) and p-dimethylaminocinnamaldehyde (1 mol.+l% excess, 1 g.) were dissolved in acetic anhydride ml.) and heated under N,N-diethylarnino,

4 reflux for five minutes. The reaction mixture was then chilled overnight and crystalline dye was filtered, washed on a Buchner funnel with acetone and dried. The yield of purified dye after two recrystallizations from methyl alcohol was 4.2 g. (44% M.P. 220-221 C.

DYE 2 Anhydro S-chloro-Z-(4-p-dimethylaminophenyl-1,3-butadienyl) 3,3 dimethyl-l-(4-sulfobutyl)-3H-indolium hyrdoxide (CHM Anhydro-5-ch1oro-2,3,3-trimethyl-1-(4-sulfobutyl)-3H indolium hydroxide (1 mol., 3,3 g.) and p-dimethylaminocinnamaldehyde (l mo1.+100% excess, 3.5 g.) were dissolved in acetic anhydride ml.) and heated under reflux for twenty minutes. The reaction mixture was then chilled overnight and the crude dye thrown out of solution by the addition of an excess of ether with stirring. The ether was decanted from the sticky dye residue and the dye obtained in crystalline form by adding acetone with stirring. The crystalline dye was filtered, washed on the Buckner funnel with acetone and dried. After two recrystallizations from fifty percent methyl alcohol and water, the yield of purified dye was 1 g. (22%), M.P. 245246 C. dec.

DYE 3 Anhydro-5-chloro-2- (4-p-methoxyphenyl-1,3=butadienyl)- 3,3-dimethyl-1-(4-sulfobuty1)-3H-indolium hydroxide 1 Dye 3 was made like Dye 2 but by using the reactants anhydro 5-chloro-2,3,3-trimethyl-l-(4-sulfobutyl)-3H-indolium hydroxide (1 mol., 3.3 g.) and p-methoxycinnamaldehyde (1 mol.+ 100% excess, 3.0 g.), and reducing the concentration of acetic anhydride to 20 ml. The yield of purified dye was 1.3 g. M.P. 297 -298 C. dec.

DYE 4 3 carboxymethylcarbamoyloxyethyl 2- (4-p-diemthylaminophenyl 1,3-butadienyl)-1,1-dimethyl-1H-benz[e] indolium iodide -CO-NHCH:COOH

1,1 dimethyl 2 (4 p dimethylaminophcnyl 1,3 butadienyl) 3 ethoxycarbonylmethylcarbamoxycthyl 1'H-benz[e]indolium iodide (1 mol., 3.33 g.) and sodium hydroxide (1 mo1.+100% excess, 0.4 g. in 2 ml. H O) were dissolved in absolute ethylalcohol (200 ml.) and the solution heated under reflux for ten minutes. The yellow precipitate that separated from the solution was then filtered, suspended in a small amount of water, the water suspension treated with acetic acid and the re-formed dye filtered ofl, washed with a small amount of acetone and dried. After two recrystallizations from aqueous methyl alcohol the yield of pure dye was 2.0 g. (627) M.P. 186-187 dec.

DYE 5 2 (4 p dimethylaminophenyl 1,3 butadienyl) 3 ethoxycarbonylmethylcarbamoyloxyethyl 1,1 dimethyl1H-benz[e]indolium iodide 1,1 dimethyl 2 (4 p dimethylaminophenyl 1,3 butadienyl) 3 hy'droxyethyl 1H benz[e]indolium iodide (1 mol., 8 g.) and carbethoxymethylisocyanate (1 mol.+300% excess, 5 g.) were mixed in dry pyridine (75 ml.) and heated under reflux for one hour. The mixture was then chilled and the crystalline dye filtered off and dried. After two recrystallizations from methyl alcohol the yield of pure dye was 0.5 g. (50%) M.P. 230-231 dec.

DYE 6 2- (4-p-dimethylaminophenyl-1, 3-butadienyl) -3-hydroxyethyl-1,1-dimethyl-1H-benz[e]indolium iodide 3 hydroxyethyl 1,1,2 trimethyl 1H benz[e]indolium bromide (1 mol., 18 g.) and p-dimethylaminocinnamaldehyde (1 mol. plus excess, 10.3 g.) were mived in absolute ethyl alcohol and the mixture heater under reflux for ten minutes. The mixture was then chilled and the dye precipitated as the iodide by adding sodium iodide with good stirring. The dye was thenfiltered off, stirred in a water suspension, filtered ofi, washed with a small amount of acetone and dried. After two recrystallizations from methyl alcohol the yield of pure dye was 12 g. (42%) M.P. 250-251 dec.

DYE 7 3-carboxyethyl-2-(4-p-dimethylaminophenyl-1,3-butadienyl -1,1-din1ethy1-1H-benz [e]indolium iodide 3 carboxyethyl 1,1,2 trimethyl-lH-benz[e]indolium iodide (1 mol., 6.14 g.) and p-dimethylaminocinnamaldehyde were mixed in ethyl alcohol and the mixture heated under reflux for one hour. The mixture was then chilled and the crude dye filtered off, washed with a small amount of acetone and dried. After two recrystallizations from ethyl alcohol the yield of pure dye 'was 4.6 g. (54%), M.P. 174175 dec.

DYE 8 Anhydro 1,1 dimethyl 2 (4-p-dimethylaminophenyl- 1,3 butadienyl) 3 (3 sulfopropyl) 1H benz[e] indolium hydroxide Anhydro 3 (3 sulfopropyl) 1,1,2 trimethyl 1H benz[e]indolium hydroxide (1 mol., 66.2 g.) and p-dimethylaminocinnamaldehyde (1 mol. plus 50% excess, 47.5 g.) were mixed in absolute ethanol (500 ml.) and heated under reflux for one hour. The mixture was then chilled over night and the crystalline dye filtered ofl, washed on a Buchner funnel with acetone and dried. The

yield of purified dye after two recrystallizations from methanol was 51 g. (51%) M.P. 238239 C.

DYE 9 This dye was prepared by a method similar to that used 6 1-(4-sulf0butyl)-3H-indolium hydroxide (1 mol.) and pmethoxycinnamaldehyde (l m0l.+100% excess), and reducing the concentration of acetic anhydride to 20 ml.

DYE 10 Anhydro-2-(4-p-dimethylaminophenyl-1,3-butadienyl)- 3,3-dimethyl-1- (4-sulfobutyl -3H-indolium hydroxide This dye was prepared by a method similar to that used to make Dye 2 but using as the reactants anhydro-2,3,3- trimethyl 1 (4 sulfobutyl)-3H-indolium hydroxide (1 mol.) and p-dimethylaminocinnamaldehyde (1 mol.+ 100% excess).

DYE 11 Anhydro 2 (4 p dimethylaminophenyl 1,3 butadienyl) 1,1 dimethyl 3 (3 sulfobutyl)-1H-benz[e] indolium hydroxide, monosulfonated 1,1,2 trimethyl 1H benZ[eJindole-monosulfonated (1 mol., 5.78 g.) and 2,4-butanesulfone (suflicient excess to form a mobile mixture) were mixed and heated over a free flame until the viscous mixture turned brownish-black in color. The mixture was then cooled and the anhydro-3- (3 sulfobutyl) 1,1,2 1H-benz[e]indolium hydroxidemonosulfonated precipitated as a grey solid by treating with an excess of acetone and stirring. At this point the hydroscopic grey solid was filtered ofl, dissolved in refluxing ethyl alcohol (100 ml.), p-dimethylaminocinnamaldehyde (1 mol., 3.5 g.) added and the mixture heated under reflux for fifteen minutes. The mixture was then chilled and the crude dye precipitated from solution by turning the mixture into acetone (300 ml.) with stirring. The solid dye was filtered off, washed with acetone and dried. After two recrystallizations from aqueous methyl alcohol and acetone the yield of pure dye was 3.5 g. (31%); melting point 289290 C. dec.

DYE 12 Anhydro 3 carboxyethyl-Z-(4-p-dimethylaminophenyl- 1,3 butadienyl) 1,1 dimethyl-lH-benz[e]indolium hydroxide, monosulfonated; pyridine salt 1,1,2 trimethyl 1H benz[e]indole-monosulfonated (1 mol., 5.78 g.) and propiolactone (suflicient excess to form a mobile mixture) were mixed and heated over a free flame until the solid went into solution and the solution turned amber in color. The mixture was then removed from heat and reaction took place causing the solution to turn dark in color with a vigorous evolution of heat. The

for Dye 2 but using the reactants anhydro-2',3,3-trimethyldark viscous mass was cooled, stirred with an excess of ether, ether decanted and the sticky residue dissolved in refluxing ethyl alcohol (200 ml.). At this point p-dimethylaminocinnamaldehyde (1 mol., 3.5 g.) was added and the mixture heated under reflux for ten minutes. The solid dye was collected and after two recrystallizations from ethanol/ pyridine the yield of pure dye was 4.5 g. (43%), M.P. 226227 C. dec.

DYE 13 2- [4-p-dirnethylaminophenyl-1,3-butadienyl] -1-ethyl-3, 3- dimethyl-3H-indolium iodide This dye was prepared by a reaction similar to that used to prepare Dye 6 excepting that 1,1,2-trimethylindolenine ethiodide and p-dimethylaminocinnamaldehyde were used. The yield of purified dye was 32%, M.P. 238239 C. with dec.

The preparation of typical intermediates used in making our dyes will further illustrate our invention.

3-hydroxyethyl-1, 1-dimethyl-1H-benz[e] indolium bromide 1,1,2-trimethyl-1H-benz[e]indole (1 mol., 10.4 g.) and 2-bromoethanol (1 mol., 6.25 g.) were mixed and heated on a steam bath for twenty-four hours. The hard cake that formed was ground under ether, suspended in acetone, filtered and dried. The yield was 15 g. (90%) M.P.=159-160 dec.

The corresponding iodide salt was prepared from the bromide by double decomposition with sodium iodide.

3-carboxyethyl-1,1,2-trimethyl-1H-benz[e] indolium iodide 1,1,2-trirnethyl-1H-benz[e]indole (1 mole. plus 100% excess, 20.9 g.) and fi-iodopropionic acid (1 mole., 10 g.) were mixed and heated on a steam bath for 12 hours. The product was then washed with either, refluxed in acetone, filtered and dried. The yield of light tan solid was 14 g. (70%) M.P. 18ll82 dec.

Anhydro-3(4-sulfobutyl)-1,1,2-trimethyl 1H benz [eJindolium hydroxide, and anhydro-3-(3-sulfopropyl)- 1,1,2-trimethyl-1H-benz[e]indolium hydroxide were prepared by the methods described in Heseltine and Brooker, US. Patent 2,895,955, issued July 21, 1959. Andre-2,3,3- trimethyl-1-(4-sulfobntyl)-3H-indolium hydroxide was prepared from 1,1,2-trimethylindole by reaction described in US. Patent 2,895,955. The corresponding -chloro derivative was prepared in the same manner but starting with 5-chloro-2,3,3-trimethyl-3H-indole.

Our dyes have light-absorbing characteristics that make them valuable for use in filter and antihalation layers of photographic elements. These characteristics are illustrated in Table I below.

TABLE I Maximum light absorption by dye Dye number occurs at a wavelength in m of 1 615 2 630 Our butadienyl dyes are distinguished from other butadienyl dyes by having maximum light absorption at wavelengths that are considerably longer than other butadienyl dyes that are outside our invention. Furthermore, the increase in depth of color with the introduction of a vinylene group is much larger with our irdolenine and benz[e]indole dyes than it is with other typical nuclei used in styryl dyes. The following table illustrates.

TABLE II.ADSORPTION MAXIMA OF -DIMETHYLAMINO- STYRYL AND p-DIMETHYLAMI OB UTENYLIDENE DYES Increase in depth of color with introduction Styryl or one dye Butadienyl vinylene Heterocyclic Nucleus (mu) dye (my) group (111,4)

0-. GzH5 X m 525.0 55cc 31.0 T

560.0 615.0 55.0 I cg, cn.

ea/ N (511M03 These data show that of the higher vinylogs only the immediate dyes absorb at wavelength longer than 600 III/1.. It is unexpected that the immediate dyes would have shifts in the spectral absorption as high as 70 mp. from the corresponding styryl (lower vinylog) dye when the shift in spectral absorption of butadienyl dyes outside our invention and their lower vinylogs is only about 31 mp.

Our dyes are readily soluble in water because of their ionic nature and are thus readily incorporated in hydrophilic colloids such as gelatin, polyvinyl alcohols, albumen, and casein which are usually used for filter and antihalation layers of photographic materials. A stock solution may be made of the dye to be used and this can be added to the hydrophilic colloid solution before it is coated.

The concentration of dye in the hydrophilic colloid may be varied considerably depending .upon the product in which the filter or antihalation layer is to be used. The proper amount of dye to be used for a given product can be determined by methods well known in the art.

In the accompanying drawing, FIGURES 1 and 2 are enlarged sectional views of photographic elements having filter layers or antihalation layers made according to our invention. As shown in FIGURE 1, a support 10 of any suitable material such as cellulose acetate, cellulose nitrate, synthetic resin materials or opaque materials such as paper, is coated with an emulsion layer 11 and an overcoating layer 12 comprising a hydrophilic colloid such as gelatin and a butadienyl dye of our invention.

FIGURE 2 illustrates a multilayer photographic element for color photography in which the support 10 is coated with sensitive layers 13, 14 and 15 which record light of the red, green and blue regions of the spectrum respectively. Between the emulsion layers 14 and 15 there is a filter layer 16 containing gelatin and a yellow butadienyl dye. This filter layer serves a purpose Well 9 known in color photography of preventing exposure of a lower layer of the element by' light which the filter layer absorbs. The dye may also: absorb light in other regions such as the ultraviolet region on the spectrum.

FIGURE 3 represents a film having an antihalation layer containing a dye of our invention. As shown therein, the support 10 carries an emulsion layer 11 on one side and an antihalation layer 17 containing a butadienyl dye on the opposite side:

FIGURE 4 represents a film having under the emulsion an antihalation layer containing a dye of our invention. As shown, the support 10 carries; an antihalation layer 18 which has been overcoated with emulsion layer 11. This antihalation layer serves the well-known purpose of absorbing light passing through the layer and its reflection from the surface of the support back to the emulsion layer.

These dyes can be advantageously used in the preparation of photographic light screening layers by dissolving the dyes in water, or a mixture of alcohol and water, and adding the resulting solution to an aqueous hydrophilic colloidal solution, or to a hydrophobic colloidal solution, e.g., cellulose acetate phthalate or the cellulose ester of dimethylamino-acetic acid before coating.

Examples of the use of the dyes of our invention are illustrated as follows:

The mg. of Dye 1 was dissolved in ml. of methanol and diluted to 20 ml. with water. This solution was added to ml. of a 10 percent photographic gelatin solution containing 0.5 ml. of saponin solution. The mixture was coated on a suitable support at a thickness that contained from ten to twenty mg. of dye per square foot.

A layer of alkali-removable cellulose acetate phthalate coated over cellulose triacetate sheeting was followed by an overcoat of the following compostion: 1.0% of Dye 2 in a mixture of 95% alcohol and 5% water.

A layer of alkali-removable cellulose acetate phthalate was coated over cellulose triacetate followed by a dye coat of the following composition: 0.4% anhydro-5-chloro-2- p dimethyl aminostyryl-3,3-dimethyl- 1-(4-sulfo'butyl)- 3H-ind0lium hydroxide, 1.0% of Dye 2 from alcoholwater.

The following examples will illustrate more fully how our dyes may be used in preparing light absorbing filter layers.

Example 1 1.5 grams of Dye 1 were dissolved in 37.5 ml. of water and this solution was added to 4.5 liters of 5% aqueous gelatin. This mixture was then coated as an antihalation backing on the reverse side of a support which has been coated with a photographic silver halide emulsion layer.

After exposure of the photographic element in the usual manner, development of the exposed material in a developer having the following composition:

N-methyl-p-aminophenol sulfate grams 2 Sodium sulfite (desiccated) do 90 Hydroquinone do 8 Sodium carbonate monohydrate do 52.2 Potassium bromide do 5 Water to make 1 liter.

followed by fixation in a conventional sodium thiosulfate fixing bath resulted in complete removal of the dye from the photographic element.

Example 2 A photographic element made as in Example 1, but using Dye 4 in place by Dye 1 was exposed. No dye color was evident in this element after development, and fixing with the solutions used in Example 1.

Example 3 A mixture of Dye l and aqueous gelatin solution as prepared in Example 1 was coated over a light-sensitive silver halide emulsion layer on a conventional support.

After exposure of the photographic element in the usual manner, development. and fixing of the exposed material in the solutions of Example 1 resulted in a complete removal of the dye color from the light filtering layer over the developed image.

Example 4 Similarly, the other dyes of our invention can be used in light filtering layers as in Example 3.

The above examples show the use of our dyes in antihalation layers and in layers overcoating the light sensitive silver halide emulsion layer; they can also be coated between light sensitive silver halide layers in multilayer photographic elements.

The novel dyes of our invention are characterized by being readily water soluble and readily bleachable by ordinary photographic developers and processing solutions. These properties make our dyes valuable for use in making light sensitive photographic elements. Our dyes are particularly valuable in light absorbing filter layers either coated over the silver halide emulsion layers, or coated between light sensitive silver halide layers, or coated on either side of the support on which the light sensitive silver halide emulsion layers are coated.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A dye having the formula:

a )nl wherein L represents a group selected from the class consisting of the hydrogen atom, and a halogen atom; Y and Y collectively represent the non-metallic atoms necessary to complete a benzindole nucleus, R and R each represent a member selected from the class consisting of a hydrogen atom and an alkyl hydrocarbon group having 1 to 4 carbon atoms, and collectively represent tetramethylene or pentamethylene, R represents a member selected from the class consisting of an alkyl hydrocarbon group having 1 to 6 carbon atoms, a carboxyalkyl group having 2 to 7 carbon atoms, a hydroxyalkyl group having 2 to 6 carbon atoms, a sulfoalkyl group having 2 to 6 carbon atoms, a carboxyalkylcarbamoyloxyalalkyl group wherein the carboxyalkyl group has 2 to 6 carbon atoms and the oxyalkyl radical has 2 to 3 carbon atoms and an alkoxycarbonylalkylcarbamoyloxyethel group wherein the alkoxy group and the alkyl group of the alkoxycarbonylalkyl group each has 1 to 2 carbon atoms, X represents an acid anion, n represents 1 or 2 and wherein n is only 1 when R contains a carboxy group or a sulfo group, and Z represents a member selected from the class consisting of a hydroxyphenyl group, an alkoxyphenyl group wherein the alkoxy group has 1 to 4 carbon atoms, and an N,N-dialkylaminophenyl group wherein alkyl is an alkyl hydrocarbon group having 1 to 4 carbon atoms.

2. A dye compound in accordance with claim 1 wherein said compound is anhydro-2-(4-p-dimethylaminophenyl- 1,1 dimethyl 1,3 butadienyl) 3 (4 sulfobutyl) 1H-benz[e]indolium hydroxide.

3. A dye compound in accordance with claim 1 wherein said compound is 3-carboxyethyl-2-(4-p-dimethylaminophenyl 1,3 butadienyl) 1,1 dimethyl 1H benz[e] indolium iodide.

4. A dye compound in accordance with claim 1 wherein said compound is anhydro-3-carzoxyethyl-2-(4-p-dimethylaminophenyl 1,3 butadienyl) 1,1 dimethyl 1H- benz[e]indo1ium hydroxide; monosulfonated pyridine salt.

5. A dye compound in accordance with claim 1 wherein said compound is 3-carboxymethylcarbamoyloxyethyl- 2 (4 p dimethylaminophenyl 1,3 butadienyl) 1,1- dimcthyl 1H-benz[e] indolium iodide.

References Cited UNITED STATES PATENTS 2,639,282 5/ 1953 Sprague et a1 260--240 12 FOREIGN PATENTS 742,112 12/1955 Great Britain.

OTHER REFERENCES 5 Ruggli et al.: Helv'Chim. Acta., v01. 18, p. 632 (1935).

JOHN D. RANDOLPH, Primary Examiner us. c1. X.R. 96--84; 260319.1, 326.12, 326.13

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,481, 927 Dated 2 December 1969 Inventor) Donald W. Heseltine/Jean E. Jones/Lewis L. Lincoln It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, Line 35 0 Y2 @\(-cH=cH) -z \N L- l 9 2 (X n-IL should read 0 Y \(-CH=GH)2-Z N $27 3? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PAGE Patent No. 3 L Dated 2 December 1969 Inventor) Donald W. Heseltine/Jean E. Jones/Lewis L. Lincoln It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column ll, line 2 3-carzoxyethyl Should read 3-carboxyethyl Signed and sealed this 20th day of April 1971.

(SEAL) fittest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attssting Officer Commissioner of Patents 

